In one of the final moments of a death penalty trial for a man convicted of killing two police detectives, a prosecutor urged members of the jury to show the defendant the kind of mercy he showed the slain officers.

Ronell Wilson “slaughtered” two innocent men, an assistant U.S. attorney, Jack Smith, said during closing arguments yesterday at U.S. District Court in Brooklyn. “We ask that you impose the penalty of death on Ronell Wilson.”

Prosecutors claimed Wilson knew that Rodney Andrews and James Nemorin were undercover officers when he shot both in the head on March 10, 2003. He was convicted of two counts of murder last month.

Repeating a characterization of Wilson as an “ultraviolent gang member,” Mr. Smith asked jurors to consider Wilson’s capacity for future violence and urged jurors to “weigh heavily” the fact that the victims were police officers.

The defense countered by saying Wilson did not know who Nemorin and Andrews were and appealed to jurors’ sympathies with a description of Wilson’s childhood: his crack-addicted mother, his tendency to suck his thumb as a teenager, and his extremely low intelligence.

Choking back tears, Wilson’s attorney, Kelley Sharkey, asked the jury to consider what they would tell loved ones when describing the case. “When they ask you, ‘How did you vote?’ tell them you voted for life,” she said.

As both sides rested, Judge Nicholas Garaufis instructed jurors on aspects of their deliberations, reminding them to weigh the evidence without bias or passion.

Around 4 p.m., as the jury filed out of the courtroom, relatives of Nemorin and Andrews began talking quietly, doing what they have done for nearly four years: wait.